In general, a master link for use in the connection of an end of a chain of a track chain link in an endless track vehicle, is firmly assembled to an distal end of the chain by means of a respective assembling components such as a pin, bush, a group of seals, and the like after performing heating, forging, through hardening, machining, and a high frequency work for a heated material, so that the master link is easy to assemble and secure sufficient strength.
However, despite its excellent assemblability, since the master link is difficult to manufacture and is high priced, it is used in the endless track vehicles such as the bulldozer that is applied with a big load and has a long corrosion exchange period.
The master link for the endless track vehicle is constructed to be disposed at a right side and a left side to form one pair, and is assembled after being divided into a front side and a rear side.
Also, the master link is manufactured through the following processes after being constructed as an integral type of the front and rear master links: heating of the material, hot forging, through hardening, primary cutting of both surfaces, boring of a press-fitting portion of the pin and a bush, drilling of a locking portion, high frequency treatment of a movement wear portion, primary cutting of a separation portion of the front and rear master link, secondary cutting of the separation portion, and tapping of a locking portion thereof.
Herein, the separation of the front and rear master links are performed such that a machined portion is cut by means of a wire cutting process in terms of the property of the machined portion (see FIG. 1), and are generally subjected to the second wire cutting work so as to secure a gap between the master link and the corresponding assembly portion (see FIG. 3) also.
However, since the machining speed of the wire cutting method was slow, and the cutting equipment is expensive, there has occurred a problem in that the machining expense was too high.